Organic ionic plastic crystals: flexible solid electrolytes for lithium secondary batteries

Abstract

The growing global demand for energy has led to the active development of efficient energy generation and storage technologies, driving the development of electrochemical devices such as high-energy density rechargeable batteries, fuel cells and solar cells. One of the essential materials for the development of high-performance electrochemical devices is the electrolyte. Currently, flammable electrolyte solutions are used, causing problems such as leakage and ignition incidents. It would be significant if the electrolyte could be replaced with a solid electrolyte, as this would eliminate these problems. In addition, with the increasing size of electrochemical devices, there is a societal demand for safer electrochemical devices, and the development of high-performance solid electrolytes is becoming more active. Although development has mainly focused on inorganic and solid polymer electrolytes, organic ionic plastic crystals (OIPCs) are beginning to attract attention as new candidates for flexible solid electrolytes. In this review, we describe OIPCs for lithium secondary batteries. Firstly, we introduce OIPCs and OIPC/polymer composites as lithium-ion conductors and discuss the effects of ionic architecture and polymer species on their ionic conduction. Secondly, we present recent progress in the development of lithium secondary batteries with OIPC-based solid electrolytes.